Studies will be continued on metabolic regulation in mammalian cardiac cells supported in tissue culture. One of the research goals will be the investigation of the control by creatine of enzymatic activities in homogenates of phosphokinase and adenylatekinase. These enzymes are involved directly in the accumulation of intercellular energy levels. Rates of synthesis of the phosphokinase enzymes under various growth conditions will be studied. And preliminary studies on the cardiotoxicity of the chemotherapeutic agent adriamycin on the cultures will be made. Mechanical studies of muscle relating striated muscle dynamics to cardiac output control will be continued.